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Oct 14, 2025
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add syntax highlighting to the REPL input #59778

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1 change: 1 addition & 0 deletions NEWS.md
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Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,7 @@ Standard library changes
#### REPL

* The Julia REPL now support bracketed paste on Windows which should significantly speed up pasting large code blocks into the REPL ([#59825])
* The REPL now provides syntax highlighting for input as you type. See the REPL docs for more info about customization.
* The display of `AbstractChar`s in the main REPL mode now includes LaTeX input information like what is shown in help mode ([#58181]).
* Display of repeated frames and cycles in stack traces has been improved by bracketing them in the trace and treating them consistently ([#55841]).

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1 change: 1 addition & 0 deletions contrib/generate_precompile.jl
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Expand Up @@ -41,6 +41,7 @@ precompile(Tuple{typeof(Base.Terminals.enable_bracketed_paste), Base.Terminals.T
precompile(Tuple{typeof(Base.Terminals.width), Base.Terminals.TTYTerminal})
precompile(Tuple{typeof(Base.Terminals.height), Base.Terminals.TTYTerminal})
precompile(Tuple{typeof(Base.write), Base.Terminals.TTYTerminal, Array{UInt8, 1}})
precompile(Tuple{typeof(Base.isempty), Base.AnnotatedString{String}}

# loading.jl - without these each precompile worker would precompile these because they're hit before pkgimages are loaded
precompile(Base.__require, (Module, Symbol))
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177 changes: 177 additions & 0 deletions stdlib/REPL/docs/src/index.md
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One thing I do wonder is if we're going to put a sample "fancier theme" in the config whether it would be better to use an example that is based on terminal colours rather than hex codes, so it blends in better with people's terminal themes as a drop-in config.

For instance, this is what I've got in my faces.toml

[julia]
macro.fg = "magenta"
symbol.fg = "magenta"
singleton_identifier.inherit = "julia_symbol"
type.fg = "yellow"
typedec.fg = "bright_blue"
comment.fg = "grey"
string.fg = "green"
string_delim.fg = "bright_green"
regex.inherit = "julia_string"
backslash_literal.fg = "magenta"
cmd.inherit = "julia_string"
cmd_delim.inherit = "julia_macro"
char.inherit = "julia_string"
char_delim.inherit = "julia_string_delim"
number.fg = "bright_magenta"
bool.fg = "light_yellow"
funcall.fg = "cyan"
broadcast = { fg = "bright_blue", weight = "bold" }
builtin.fg = "yellow"
operator = "blue"
comparator.fg = "bright_blue"
assignment.fg = "bright_red"
keyword.fg = "red"

[julia.rainbow_paren]
1.fg = "bright_green"
2.fg = "bright_blue"
3.fg = "bright_red"
[julia.rainbow_bracket]
1.fg = "blue"
2.fg = "bright_magenta"
[julia.rainbow_curly]
1.fg = "bright_yellow"
2.fg = "yellow"

That said, Monokai is rather inoffensive and most people use a dark theme, so I'm probably overthinking this.

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I don't really have an opinion, I just wanted to make it clear that it can be customized and how it is done. Monokai was the first the came to my head.

Original file line number Diff line number Diff line change
Expand Up @@ -533,6 +533,183 @@ mmap(file::AbstractString, ::Type{T}, len::Integer) where T<:BitArray in Mmap at
mmap(file::AbstractString, ::Type{T}, len::Integer, offset::Integer; grow, shared) where T<:BitArray in Mmap at Mmap/src/Mmap.jl:322
```

## Syntax Highlighting

The REPL provides syntax highlighting for input as you type.
Syntax highlighting is enabled by default but can be disabled in your `~/.julia/config/startup.jl`:

```julia
atreplinit() do repl
repl.options.style_input = false
end
```

### Customizing Syntax Highlighting Colors

The default syntax highlighting theme is quite conservative but can be customized using a TOML file `faces.toml` (https://julialang.github.io/StyledStrings.jl/dev/#stdlib-styledstrings-face-toml) in `.julia/config` (or by explicitly loading the faces from a face toml file).


<details>
<summary>Example: Monokai color theme (click to expand)</summary>

```toml
# Monokai color theme for Julia syntax highlighting

[julia_macro]
foreground = "#A6E22E"

[julia_symbol]
foreground = "#AE81FF"

[julia_singleton_identifier]
inherit = "julia_symbol"

[julia_type]
foreground = "#66D9EF"

[julia_typedec]
foreground = "#66D9EF"
weight = "bold"

[julia_comment]
foreground = "#75715E"
italic = true

[julia_string]
foreground = "#E6DB74"

[julia_regex]
inherit = "julia_string"

[julia_backslash_literal]
foreground = "#FD971F"
inherit = "julia_string"

[julia_string_delim]
foreground = "#E6DB74"
weight = "bold"

[julia_cmdstring]
inherit = "julia_string"

[julia_char]
inherit = "julia_string"

[julia_char_delim]
inherit = "julia_string_delim"

[julia_number]
foreground = "#AE81FF"

[julia_bool]
foreground = "#AE81FF"
weight = "bold"

[julia_funcall]
foreground = "#A6E22E"

[julia_broadcast]
foreground = "#F92672"
weight = "bold"

[julia_builtin]
foreground = "#66D9EF"
weight = "bold"

[julia_operator]
foreground = "#F92672"

[julia_comparator]
inherit = "julia_operator"

[julia_assignment]
foreground = "#F92672"
weight = "bold"

[julia_keyword]
foreground = "#F92672"
weight = "bold"

[julia_parentheses]
foreground = "#F8F8F2"

[julia_unpaired_parentheses]
background = "#F92672"
foreground = "#F8F8F0"
weight = "bold"

[julia_error]
background = "#F92672"
foreground = "#F8F8F0"

[julia_rainbow_paren_1]
foreground = "#A6E22E"
inherit = "julia_parentheses"

[julia_rainbow_paren_2]
foreground = "#66D9EF"
inherit = "julia_parentheses"

[julia_rainbow_paren_3]
foreground = "#FD971F"
inherit = "julia_parentheses"

[julia_rainbow_paren_4]
inherit = "julia_rainbow_paren_1"

[julia_rainbow_paren_5]
inherit = "julia_rainbow_paren_2"

[julia_rainbow_paren_6]
inherit = "julia_rainbow_paren_3"

# Rainbow brackets
[julia_rainbow_bracket_1]
foreground = "#AE81FF"
inherit = "julia_parentheses"

[julia_rainbow_bracket_2]
foreground = "#E6DB74"
inherit = "julia_parentheses"

[julia_rainbow_bracket_3]
inherit = "julia_rainbow_bracket_1"

[julia_rainbow_bracket_4]
inherit = "julia_rainbow_bracket_2"

[julia_rainbow_bracket_5]
inherit = "julia_rainbow_bracket_1"

[julia_rainbow_bracket_6]
inherit = "julia_rainbow_bracket_2"

# Rainbow curlies
[julia_rainbow_curly_1]
foreground = "#F92672"
inherit = "julia_parentheses"

[julia_rainbow_curly_2]
foreground = "#A6E22E"
inherit = "julia_parentheses"

[julia_rainbow_curly_3]
inherit = "julia_rainbow_curly_1"

[julia_rainbow_curly_4]
inherit = "julia_rainbow_curly_2"

[julia_rainbow_curly_5]
inherit = "julia_rainbow_curly_1"

[julia_rainbow_curly_6]
inherit = "julia_rainbow_curly_2"
```

</details>

For a complete list of customizable faces, see the [JuliaSyntaxHighlighting package documentation](https://julialang.github.io/JuliaSyntaxHighlighting.jl/dev/).

## Customizing Colors

The colors used by Julia and the REPL can be customized, as well. To change the
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96 changes: 74 additions & 22 deletions stdlib/REPL/src/LineEdit.jl
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Expand Up @@ -4,10 +4,13 @@ module LineEdit

import ..REPL
using ..REPL: AbstractREPL, Options
using ..REPL.StylingPasses: StylingPass, SyntaxHighlightPass, RegionHighlightPass, EnclosingParenHighlightPass, StylingContext, apply_styling_passes, merge_annotations

using ..Terminals
import ..Terminals: raw!, width, height, clear_line, beep

using StyledStrings

import Base: ensureroom, show, AnyDict, position
using Base: something

Expand Down Expand Up @@ -58,6 +61,7 @@ mutable struct Prompt <: TextInterface
on_done::Function
hist::HistoryProvider # TODO?: rename this `hp` (consistency with other TextInterfaces), or is the type-assert useful for mode(s)?
sticky::Bool
styling_passes::Vector{StylingPass} # Styling passes to apply to input
end

show(io::IO, x::Prompt) = show(io, string("Prompt(\"", prompt_string(x.prompt), "\",...)"))
Expand Down Expand Up @@ -565,6 +569,8 @@ function maybe_show_hint(s::PromptState)
return nothing
end

max_highlight_size::Int = 10000 # bytes

function refresh_multi_line(s::PromptState; kw...)
if s.refresh_wait !== nothing
close(s.refresh_wait)
Expand Down Expand Up @@ -611,6 +617,42 @@ function refresh_multi_line(termbuf::TerminalBuffer, terminal::UnixTerminal, buf
reader isa Base.TTY && !Base.ispty(reader)::Bool
else false end

# Get the styling passes from the prompt
prompt_obj = nothing
if prompt isa PromptState
prompt_obj = prompt.p
elseif prompt isa PrefixSearchState || prompt isa SearchState
if isdefined(prompt, :parent) && prompt.parent isa Prompt
prompt_obj = prompt.parent
end
end

styled_buffer = AnnotatedString("")
if buf.size > 0 && buf.size <= max_highlight_size
full_input = String(buf.data[1:buf.size])
if !isempty(full_input)
passes = StylingPass[]
context = StylingContext(buf_pos, regstart, regstop)

# Add prompt-specific styling passes if the prompt has them and styling is enabled
enable_style_input = prompt_obj === nothing ? false :
(isdefined(prompt_obj, :repl) && prompt_obj.repl !== nothing ?
prompt_obj.repl.options.style_input : false)

if enable_style_input && prompt_obj !== nothing
append!(passes, prompt_obj.styling_passes)
end

if region_active
push!(passes, RegionHighlightPass())
end

if !isempty(passes)
styled_buffer = apply_styling_passes(full_input, passes, context)
end
end
end

# Now go through the buffer line by line
seek(buf, 0)
moreinput = true # add a blank line if there is a trailing newline on the last line
Expand All @@ -636,12 +678,26 @@ function refresh_multi_line(termbuf::TerminalBuffer, terminal::UnixTerminal, buf
llength = textwidth(line)
slength = sizeof(line)
cur_row += 1
# lwrite: what will be written to termbuf
lwrite = region_active ? highlight_region(line, regstart, regstop, written, slength) :
line

# Extract the portion of styled_buffer corresponding to this line.
if !isempty(styled_buffer)
# Calculate byte positions for this line in the buffer
line_start_byte = written + 1
line_end_byte = written + slength

# Convert to valid character indices (handles UTF-8 boundaries)
start_idx = thisind(styled_buffer, line_start_byte)
end_idx = thisind(styled_buffer, line_end_byte)

lwrite = @view styled_buffer[start_idx:end_idx]
else
lwrite = line
end

written += slength
cmove_col(termbuf, lindent + 1)
write(termbuf, lwrite)

write(IOContext(termbuf, :color => hascolor(terminal)), lwrite)
# We expect to be line after the last valid output line (due to
# the '\n' at the end of the previous line)
if curs_row == -1
Expand Down Expand Up @@ -692,18 +748,6 @@ function refresh_multi_line(termbuf::TerminalBuffer, terminal::UnixTerminal, buf
return InputAreaState(cur_row, curs_row)
end

function highlight_region(lwrite::Union{String,SubString{String}}, regstart::Int, regstop::Int, written::Int, slength::Int)
if written <= regstop <= written+slength
i = thisind(lwrite, regstop-written)
lwrite = lwrite[1:i] * Base.disable_text_style[:reverse] * lwrite[nextind(lwrite, i):end]
end
if written <= regstart <= written+slength
i = thisind(lwrite, regstart-written)
lwrite = lwrite[1:i] * Base.text_colors[:reverse] * lwrite[nextind(lwrite, i):end]
end
return lwrite
end

function refresh_multi_line(terminal::UnixTerminal, args...; kwargs...)
outbuf = IOBuffer()
termbuf = TerminalBuffer(outbuf)
Expand Down Expand Up @@ -999,7 +1043,9 @@ function edit_insert(s::PromptState, c::StringLike)
offset += position(buf) - beginofline(buf) # size of current line
spinner = '\0'
delayup = !eof(buf) || old_wait
if offset + textwidth(str) <= w && !(after == 0 && delayup)
# Disable fast path when syntax highlighting is enabled
use_fast_path = offset + textwidth(str) <= w && !(after == 0 && delayup) && !options(s).style_input
if use_fast_path
# Avoid full update when appending characters to the end
# and an update of curs_row isn't necessary (conservatively estimated)
write(termbuf, str)
Expand Down Expand Up @@ -2226,6 +2272,13 @@ function replace_line(s::PrefixSearchState, l::Union{String,SubString{String}})
nothing
end

function write_prompt(terminal, s::SearchState, color::Bool)
failed = s.failed ? "failed " : ""
promptstr = s.backward ? "($(failed)reverse-i-search)`" : "($(failed)forward-i-search)`"
write(terminal, promptstr)
return textwidth(promptstr)
end

function refresh_multi_line(termbuf::TerminalBuffer, s::SearchState)
buf = IOBuffer()
unsafe_write(buf, pointer(s.query_buffer.data), s.query_buffer.ptr-1)
Expand All @@ -2236,9 +2289,7 @@ function refresh_multi_line(termbuf::TerminalBuffer, s::SearchState)
write(buf, read(s.response_buffer, String))
buf.ptr = offset + ptr - 1
s.response_buffer.ptr = ptr
failed = s.failed ? "failed " : ""
ias = refresh_multi_line(termbuf, s.terminal, buf, s.ias,
s.backward ? "($(failed)reverse-i-search)`" : "($(failed)forward-i-search)`")
ias = refresh_multi_line(termbuf, s.terminal, buf, s.ias, s)
s.ias = ias
return ias
end
Expand Down Expand Up @@ -2823,10 +2874,11 @@ function Prompt(prompt
on_enter = default_enter_cb,
on_done = ()->nothing,
hist = EmptyHistoryProvider(),
sticky = false)
sticky = false,
styling_passes = StylingPass[])

return Prompt(prompt, prompt_prefix, prompt_suffix, output_prefix, output_prefix_prefix, output_prefix_suffix,
keymap_dict, repl, complete, on_enter, on_done, hist, sticky)
keymap_dict, repl, complete, on_enter, on_done, hist, sticky, styling_passes)
end

run_interface(::Prompt) = nothing
Expand Down
8 changes: 7 additions & 1 deletion stdlib/REPL/src/REPL.jl
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Expand Up @@ -66,6 +66,8 @@ using Base.Terminals
abstract type AbstractREPL end

include("options.jl")
include("StylingPasses.jl")
using .StylingPasses

include("LineEdit.jl")
using .LineEdit
Expand Down Expand Up @@ -1329,7 +1331,11 @@ function setup_interface(
(repl.envcolors ? Base.input_color : repl.input_color) : "",
repl = repl,
complete = replc,
on_enter = return_callback)
on_enter = return_callback,
styling_passes = StylingPasses.StylingPass[
StylingPasses.SyntaxHighlightPass(),
StylingPasses.EnclosingParenHighlightPass()
])

# Setup help mode
help_mode = Prompt(contextual_prompt(repl, HELP_PROMPT),
Expand Down
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